dif.variance: DIF Variance
Description
This function calculates the variance of DIF effects, the so called
DIF variance (Longford, Holland & Thayer, 1993).Usage
dif.variance(dif, se.dif, items = paste("item", 1:length(dif), sep = "") )Arguments
dif
Vector of uniform DIF effects
se.dif
Standard error of uniform DIF effects
items
Optional vector of item names
Value
- A list with following entries
- weighted.DIFSDWeighted DIF standard deviation
- unweigted.DIFSDDIF standard deviation
- mean.se.difMean of standard errors of DIF effects
- eb.difEmpirical Bayes estimates of DIF effects
References
Longford, N. T., Holland, P. W., & Thayer, D. T. (1993).
Stability of the MH D-DIF statistics across populations.
In P. W. Holland & H. Wainer (Eds.). Differential
Item Functioning (pp. 171-196). Hillsdale, NJ: Erlbaum.